Japan's agriculture minister hanged himself today hours before he was due to face questioning over an alleged expenses scandal, police and officials said. Toshikatsu Matsuoka, 62, is the first Japanese minister to commit suicide since the days immediately following the country's surrender in the second world war.

Mr Matsuoka, who faced severe pressure over a series of alleged misdeeds, was found unconscious inside his Tokyo apartment, the chief cabinet secretary, Yasuhisa Shiozaki, told reporters.

The minister died later in hospital. An autopsy showed he had hanged himself, Tokyo police said.

They refused to confirm reports that Mr Matsuoka had used a rope resembling a dog lead and had been dressed in pyjamas, and had left a series of suicide notes, including ones addressed to Japan's prime minister, Shinzo Abe, and the public, apologising for his actions.

Mr Abe, who faces key elections for the upper house of parliament in July, looked shaken after visiting the hospital where Mr Matsuoka died.

"The effects on the cabinet will be great," Mr Abe told reporters. "I feel deeply conscious of my responsibility as prime minister, and as the one who appointed him."

Mr Matsuoka had been scheduled to appear before a parliamentary committee this afternoon to answer questions about allegations he claimed the equivalent of around £120,000 in utility bills for a parliamentary office where such services are supplied free. He also faced allegations over other issues, among them political contributions.

Shortly after taking office, the minister had to apologise for declaring several thousand pounds in donations from a scandal-linked political group.

Mr Abe had defended Mr Matsuoka, saying the minister acted correctly and was not about to be sacked. However, some Japanese newspaper reports said there were calls for his resignation within the ruling party.

It is a further blow for Mr Abe's beleaguered government. A new opinion poll today showed his approval rating at 32%, down 11 percentage points from a similar survey in April.

Japan's suicide rate is among the highest in the industrialised world. More than 32,000 Japanese nationals killed themselves in 2004.